Case Number : Case 2202 - 16 November 2018 Posted By: Dr. Richard Carr

Follicular Basaloid Hamartoma

My differential diagnosis is benign follicular tumorlet vs. another basal cell carcinoma. I favor follicular tumorlet because of the convoluted architecture. My understanding is that basaloid follicular hamartoma is a evenly spaced multifocal lesion in the superficial dermis, unlike what we see here. But please correct me if I am wrong...

Acquired  Basaloid Follicular Hamartoma is a well known incidentale finding in skin around BCC. No BerEp4, no epithelial-stromal clefts, no mucin are more in keeping with BFH. No keratin cysts,no specialized(papillary mesenchimal body-like)stroma, no peripheral palizade make  me favor BFH over TE.  So agree with Alex. 

Basaloid Follicular Hamartoma

Agree..basaloid follicular hamartoma

Whoops sorry for the late response. It's not BFH (i'd expect BFH to be BerEP4+ & CD10+ (epithelilial) just like BCC but have some dendritic Merkel cells on CK20).

So I thought the lesion was a mantleoma (mantle cell hyperplasia, folliculocentric basaloid proliferation and basaloid follicular hyperplasia or follicular tumourlet are probably all synonymous). I thought there was a hint of sebaceous differentiation here. 

BTW papillary mesenchymal cells are not present in either BFH or mantleoma.